Gerard Butler has had the distinction of starring or co-starring in many big-budget Hollywood productions, from The Phantom of the Opera to Timeline, Tom Raider II to Reign of Fire, and yet he still hasn't quite broken through into the realm of major stardom. That is likely to change, however, when his next film, the adaptation of Frank Miller's graphic novel 300, is released in March.

IGN Movies sat in on a 300 press conference in New York this past Monday, where the actor discussed the film and his role as Leonidas, the Spartan king, at length. (For more on the film from Miller and director Zack Snyder, click here for our coverage of the L.A. press event from last week.) When asked how Butler got the role of Leonidas, he cracked that "having to go through the whole casting couch with Frank Miller  not a pretty sight," before telling the full (hopefully, truer) story.

"I heard about [300] when they offered it to me!" he laughs, before looking over at Miller and saying, "Sorry, [it's my] comic book favorite ever! 300, me, mom, Christmas, birthday! 300. 300. 300! Batman! It wasn't even written yet! No, I knew of the comic book but I hadn't read it, and what happened was I was in speaking to [Warner Bros. exec] Greg Silverman about something else, and Greg said, 'We've got this really cool project 300.' And as I heard the name 300, I thought, 'What a cool title for a project.' And he explained what it was about and then they set up a meeting with Zack, and him and I had the craziest meeting in the Valley where we were both jumping about. I think people thought we had just been let out of the nuthouse, as we were describing the physicality and the whole story and we just connected."

300 details the true story from ancient times of the 300 Spartan soldiers who faced the unbeatable forces of the overwhelming Persian army at the Battle of Thermopylae. You might describe the tale as the Dirty Dozen in togas though in Butler's eyes, it's so much more than that.

"The script was written so poetically, in a way that you kind of felt, 'How can you film this?'" he recalls. "It was like, 'The dying groans rushed from the body,' or, 'rushed from ' Uh, whatever the f**k it said! O.K., how are you going to film that? At the same time it just gave the script a really unusual, edgy, beautiful kind of poetic feel to it, and so after we had that meeting, you just know there's that gut feeling. I've been excited about different projects, but there was just something about this one. And then they showed me the trailer that [they] shot, which blew my mind, and then of course I immediately went into panic mode. I was jumping over the couch of [producer] Mark Canton's office, jumping on it again, going, 'You've got to let me do this!'"

Obviously they did let him do it, and the result  judging by the 30 minutes or so of footage screened at the Q&A  is pretty amazing. Shot in a similar style as Robert Rodriguez's Sin City, the entire picture was filmed on green screen sets with the digitally rendered backgrounds added to the action in postproduction. The process allows Snyder to capture a highly-stylized reality, but that's not the only technical wizardry at work in the film. One scene glimpsed at the event depicts, seemingly in a single shot, Leonidas leading his troops into a battle, with the King charging front and center and taking out a good half-dozen Persians one at a time. It's a very cool scene, but one that Butler almost had to sit out.

"The shot where I'm kind of marching through, I almost never did that," he says. "I had trained so hard for this particular piece, and it was 15 guys and it all worked fine in the gym when Johnny comes [at me] and then David and then Chad. But then suddenly you dress them all the same as Persians and you're like, 'Who the fuck is this? Ahhhh!' So at the last minute it looked like we were running out of time, and Zack came over to me and said, 'Look, maybe we should use a stuntman.' And I think he just didn't know how badass I was yet! And it broke my heart. So he said, 'Why don't you go ahead and warm up?' And I don't know what happened; I guess [he] probably saw me up there and said, 'You know, maybe we'll take a gamble with this.' And it went great."

A technical glitch with the camera, however, meant that the shot (achieved in two lengthy shots, in fact, that would be seamlessly cut together in post to appear as a single take) was useless and would have to be redone.

"Anyway, the whole thing was f**ked up," laughs the actor. "And it was after Christmas, and I'm going home to Scotland and I'm going to have a few Christmas puddings, and I'm not going to be keeping up with the training quite so much. So I was like, 'Do it now! Do it before Christmas!' So [the final version] was actually after Christmas, after a few Christmas puddings. It worked great, but there was something about the first time, I think especially because it wasn't supposed to happen for me. That was the first day with the big battle where everyone was involved, and the testosterone, the excitement, the passion of every person was incredible."

Butler has nothing but praise for his director, who has already demonstrated his keen visual sensibilities through his work on the Dawn of the Dead remake. Working from the original comic book artwork (by Miller, with painted colors by Lynn Varley), Snyder made up a "massive portfolio of every shot" for the storyboards, which the team accessed and, according to Butler, often took their inspiration from as well  including the actors.

"He won't tell you because he's too humble, but Zack is so incredibly prepared," says Butler. "[We were] working from this incredible source material because I think that in just three drawings in this comic, you so got who these guys were, what they were made of, the world that they lived in, and the kind of people they were. So it was incredibly revealing at every moment, including the physicality and shape, and we would often refer back to that, for me especially, because you so got a feeling it was Leonidas, the different ways he'd been drawn and represented. It just felt like the way Zack had storyboarded it that you knew in a heartbeat that he understood the absolute essence of what this was about, and just completely enriched it and extended it and made it incredibly filmic. We all knew we were working with great stuff."

Taking on the role of Leonidas also meant that Butler would have to look like he could kick some serious ass, so he swore to Snyder and the producers that he would get in peak physical condition if they gave him the part. Of course, once he got the job, as he recalls, he said, "Oh, f**k, now I have to do it. I know that process, getting out of bed that day and you know you've got a s**t-load to do, but this was going to extend over eight months." He trained six hours a day, lifting weights with his stunt double on the set everyday, but also preparing for the shoot for four or five months in L.A., working with the film's trainer and his own personal trainer as well.

"One of my main ambitions was not to be that actor standing up there with a bunch of stunt guys who are really f**king tough, but to be that guy, with the stunt guys going, 'S**t, look at him,'" he says. "And for me one of the first things is always the physicality. There was a strength and a power and a testosterone on that set in Montreal that I've never experienced before, and as the King is slightly mad there are those moments where you go beyond being a Spartan where you realize how intense and passionate and, let's face it, how f**king nuts these guys were."